The next token of social improvement that is observable is in the tumuli, or grave-mounds, which may be referred to a period somewhat later than that of the shell-mounds. These contain indications that the people who constructed them possessed some important elements necessary to their social progress. They had a certain amount of time to spare after providing for their daily wants, and they did not spend that time exclusively in idleness. The erection of these mounds must have been a work of considerable labour, and they often contain highly finished implements and ornaments, which must have been put there for the use of the dead. They are evidences that no little honour was sometimes shown to the dead; so that some sort of religion must have existed amongst the people who constructed the ancient grave-mounds. The importance of this element in early society is evident if we inquire further for whom and by whom these mounds were erected. Now, they are not sufficiently numerous, and are far too laborious in their construction, to have been the ordinary tombs of the common people. They were probably tombs erected for chiefs or captains of tribes to whom the tribes were anxious to pay especial honour. We do not know at all how these separate tribes or clans came into existence, and what bonds united their members together; but so soon as we find a tribe erecting monuments in honour of its chiefs, we conclude that it has attained a certain amount of compactness and solidity in its internal relations. Amongst an uneducated people there is probably no stronger tie than that of a common faith, or a common subject of reverence. It is impossible not to believe, then, that the people who made these great, and in some cases elaborately constructed tombs, would continue ever after to regard them as in some sort consecrated to the great chiefs who were buried under them. Each tribe would have its own specially sacred tombs, and perhaps we may here see a germ of that ancestor-worship which may be traced in every variety of religious belief. It has been supposed by some that a certain amount of [Sidenote: Barter.]